package study.nzy.com.studydemo.utils;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {

    static final String DATABASE_NAME = "MyDatabase.db";

    static final String TAB_NAME = "users";

    public static final String FIELD_NAME = "name";
    public static final String FIELD_PASSWORD = "password";
    public static final String FIELD_AGE = "age";

    SQLiteDatabase db;

    public DBHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);  // 参数为数据库名称，版本号
        db = getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        String createTableSQL = "CREATE TABLE "+TAB_NAME+" (" +
                "id INTEGER PRIMARY KEY AUTOINCREMENT, "
                +FIELD_NAME+" TEXT, "
                +FIELD_PASSWORD+" TEXT,"
                +FIELD_AGE+" INTEGER)";
        sqLiteDatabase.execSQL(createTableSQL);
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }

    public long addUser(ContentValues values){
        return db.insert(TAB_NAME,null,values);
    }

    public int updateByName(String name,ContentValues values){
        return db.update(TAB_NAME,values,FIELD_NAME + " = ?", new String[]{name});
    }

    public int delete(String name){
        return db.delete(TAB_NAME,FIELD_NAME + " = ?", new String[]{name});
    }

    public String findPasswordByName(String name){
        String pwd = null;
        String selection = FIELD_NAME + " = ?";
        Cursor cursor = db.query(TAB_NAME, null, selection, new String[]{name}, null, null, null);
        if (cursor!=null && cursor.moveToFirst()){
            pwd = cursor.getString(2);
            cursor.close();
        }
        return pwd;
    }

    public void closeDB(){
        if(db!=null && db.isOpen()){
            db.close();
        }
    }
}
